Ways to Reduce the Harmful Effects of Sun Glare

During the height of summer sunshine (and heat!), it’s helpful to discuss the importance of eye protection, including ways to reduce the harmful effects of sun glare.

Fundamentally, we need light to see. Approximately 80% of all information we take in is received through the sense of sight. However, too much light – and the wrong kind of light – can create glare, which can affect our ability to take in information, analyze it, and make sense of our surroundings.

Facts about Sunlight

Every type of light has advantages and disadvantages, and sunlight is no exception:

Advantages:

• Sunlight is the best, most natural light for most daily living needs.
• Sunlight is continuous and full-spectrum: the sun’s energy at all wavelengths is equal and it contains all wavelengths of light (explained below).

Disadvantages:

• It is difficult to control the brightness and intensity of sunlight.
• Sunlight can create glare, which can be problematic for many people who have low vision.
• Sunlight is not always consistent or reliable, such as on cloudy or overcast days.

Visible Light and Light Rays

An important factor to consider is the measurement of visible light and light rays, beginning with the definition of a nanometer:

• A nanometer (nm) is the measurement of a wavelength of light.
• A wavelength is the distance between two successive wave crests or troughs:

Wavelength - glare

• A nanometer = 1/1,000,000,000 of a meter, or one-billionth of a meter. It’s very small!

The human visual system is not uniformly sensitive to all light rays. Visible light rays range from 400 nm (shorter, higher-energy wavelengths) ? 700 nm (longer, lower-energy wavelengths).
Visible Light Spectrum - glare
The visible light spectrum occupies just one portion of the electromagnetic spectrum, however:

• Below blue-violet (400 nm and below), is ultraviolet (UV) light.
• Above red (700 nm and above), is infrared (IR) light.
• Neither UV nor IR light is visible to the human eye.

Ultraviolet Light and Blue Light

Ultraviolet (UV) light has several components:

• Ultraviolet A, or UVA (320 nm to 400 nm): UVA rays age us.
• Ultraviolet B, or UVB (290 nm to 320 nm): UVB rays burn us.
• Ultraviolet C, or UVC (100 nm to 290 nm): UVC rays are filtered by the atmosphere before they reach us.

Blue light rays (400 nm to 470 nm) are adjacent to the invisible band of UV light rays:

• There is increasing evidence that blue light is harmful to the eye and can amplify damage to retinal cells.
• You can read more about the effects of blue light at Artificial Lighting and the Blue Light Hazard at Prevent Blindness.

A new study from the National Eye Institute confirms that sunlight can increase the risk of cataracts and establishes a link between ultraviolet (UV) rays and oxidative stress, the harmful chemical reactions that occur when cells consume oxygen and other fuels to produce energy.

Sunlight and Glare

Glare is light that does not help to create a clear image on the retina; instead, it has an adverse effect on visual comfort and clarity. Glare is sunlight that hinders instead of helps. There are two primary types of glare.

Disability glare

• Disability (or veiling) glare is sunlight that interferes with the clarity of a visual image and reduces contrast.
• Sources of disability glare include reflective surfaces (chrome fixtures, computer monitors, highly polished floors) and windows that are not covered with curtains or shades.

Discomfort glare

• Discomfort glare is sunlight that causes headaches and eye pain. It does not interfere with the clarity of a visual image.
• Sources of disability glare include the morning and evening positions of the sun; snow and ice; and large bodies of water, (including swimming pools).

Controlling Glare

You can protect your eyes from harmful sunlight and minimize the effects of glare by using a brimmed hat or visor in combination with absorptive lenses.

• Absorptive lenses are sunglasses that filter out ultraviolet and infrared light, reduce glare, and increase contrast. They are recommended for people who have low vision and are also helpful for people with regular vision.
• Lens colors include yellow, pink, plum, amber, green, gray, and brown. Ultra-dark lenses are not the only choice for sun protection.
• Lens tints in yellow or amber are recommended for controlling blue light.
NoIR Medical Technologies: NoIR (No Infra-Red) filters absorb UVA/UVB radiation and also offer IR light protection.
Solar Shields: Solar Shields absorb UVA/UVB radiation and are available in prescription lenses.
• You can find absorptive lenses at a specialty products store, an “aids and appliances store” at an agency for the visually impaired, or a low vision practice in your area. Before you purchase, it’s always best to try on several different tints and styles to determine what works best for you.

More Recommendations

• Always wear sunglasses outside, and make sure they conform to current UVA/UVB standards.
• Be aware that UV and blue light are still present even when it is cloudy or overcast.
• Make sure that children and older family members are always protected with UVA/UVB-blocking sunglasses and brimmed hats or visors.

Maureen Duffy-editedMaureen A. Duffy, CVRT
Social Media Specialist, visionaware.org
Associate Editor, Journal of Visual Impairment & Blindness
Adjunct Faculty, Salus University/College of Education and Rehabilitation

Four Tips For Buying Sunglasses

4/29/14

May will be here this week, and in Southern California we are looking at bright, sun-filled days with temperatures in the upper 80s and low 90s. This means that thousands will be heading to the beaches or their own backyards to enjoy the warm weather.

Now is the perfect time to review one of the biggest contributing factors to vision loss – sun exposure. And it’s not just about sunglasses, but also brimmed hats.

from esty.com
from esty.com

First let’s talk about sunglasses. There are three things to think about when selecting your sunglasses:
1. Lens tint
2. UV protection
3. Glare
4. Frames

Lens Tint
There is a misconception that the darker your sunglass lens, the better protection for your eyes. No true. The color or darkness of your lens is personal preference and often based on the activity you are doing while wearing sunglasses or the sun conditions. At the beach in bright sunlight you are subject to more reflective light and may prefer dark amber, copper or brown lens, if you are on the ski slopes when the skies are overcast you may prefer yellow or orange lens to increase contrast and fight “flat light.” If you are looking to increase contrast on a partially cloudy day, and if you don’t mind distorted color perception, you might prefer amber or rose lenses.

Other considerations include mirrored sun lenses that can block 10-15% more of the sun’s visible rays, or photochromic lenses that darken automatically when you go outside and then quickly become lighter when you come inside.

UV Protection
While darker lenses don’t offer better eye protection, controlling the UV exposure does. Research has found links that extended exposure to UVA and UVB rays can result in eye damage such as cataracts, photokeratitis and macular degeneration. By wearing sunglasses that block these harmful rays your eyes should remain healthier as you age. Also know that some parts of the country receive more UV rays than others – here is a wonderful chart from The Vision Council to let you see how your location rates.

Glare
Another problem when out in the sun, and especially driving, is glare. Making sure your lenses are polarized is a great help. They work by only letting in specific amounts of light at certain angles and reducing the brightness of that light.

Because I am light sensitive I find I use polarized lenses when I am reading outside is helpful. The reflected light from the page of a book can cause me to squint or fatigue my eyes if I read for a long period of time. The only other option is using a paper-ink e-reader which also helps cut down on glare.

Another way to deal with glare is the use of an anti-reflective (AR) coating on your lenses. It reduces eye stain by preventing light from reflecting off lens surfaces. When applied to the back of your lenses it can help with problems when the sun is behind you or to your side.

Frames
Not all light hits your eyes from directly in front. It can come through the top, sides and bottom of your frames. The smaller the frames, the more unfiltered light makes its way to your eyes. This is where a brimmed hat can help keep the sun coming in from the top while also providing protection for your face.

Fitovers - Auroa in Claret
Fitovers – Auroa in Claret

To provide you with the maximum protection, “fit-over” sunglasses, that you can wear over your regular prescription glasses, are a great idea and more economical. Cocoons Eyewear and Fitovers Eyewear are two of several companies that make them. They filter the light from the top, sides and even below to give you the maximum protection and come in a wide variety of lens colors. It is also nice not to have to get new sunglasses when your eyeglass prescription changes.

Whatever frames you choose make sure they fit properly and will not keep sliding down your nose or fall of when being active. You may even want to purchase a band-style foamed neoprene retainer that attaches at both temples, sometimes known as a gator.

Also remember, it is not just the direct sunlight you need to worry about. Water reflects up to 100% of the harmful UV rays, dry sand and concrete up to 25% and even grass reflects up to 3%.

Susan DeRemerSusan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation